Field of the Invention
The invention relates generally to vehicle suspensions and, more specifically, to a system for adjusting operational characteristics of a vehicle suspension system.
Description of the Related Art
Vehicle suspension systems typically include a spring component or components and a damping component or components. Often, mechanical springs, like helical springs, are used with some type of viscous fluid-based damping mechanism, the spring and damper being mounted functionally in parallel. In some instances a spring may comprise pressurized gas and features of the damper or spring are user-adjustable, such as by adjusting the air pressure in a gas spring. A damper may be constructed by placing a damping piston in a fluid-filled cylinder (e.g., liquid such as oil). As the damping piston is moved in the cylinder, fluid is compressed and passes from one side of the piston to the other side. Often, the piston includes vents there-through which may be covered by shim stacks to provide for different operational characteristics in compression or extension.
Despite efforts to educate product managers, retailers, and end consumers on the importance of proper initial vehicle suspension set up, it is evident at event support and trail side encounters that many vehicles such as mountain bikes and motorcycles are ridden with improper initial suspension settings. An important initial setting is suspension “sag,” which is the measured distance a shock absorber compresses while the rider, preferably wearing intended riding gear, is seated on, e.g., a bicycle, motorcycle, or four-wheeled vehicle in a riding position compared to a fully extended suspension position. Suspension sag also applies to all-terrain vehicles (ATVs), trucks, and other vehicles equipped with a suspension. Getting the sag setting correct allows the wheels or vehicle suspension to react to negative terrain features (i.e., dips requiring suspension extension) without the entire vehicle “falling” into such terrain features. Often any attention that is paid to the initial sag setting is focused on the rear suspension, especially in motorcycle applications, but making sure that both the front and rear sag settings are correct is equally important.
Another important initial setting is the rebound damping setting for the rear and front vehicle suspensions. Rebound damping dissipates stored system spring energy after a suspension compression event and results in a controlled rate of return of the suspension to a more extended condition. Preventing the suspension from rebounding too quickly is an important aspect of the quality of vehicle suspension setup. In the case of rear suspension, an improper amount of rebound damping can result in the rear of the vehicle “kicking” off the ground and pitching the rider forward after encountering a bump or sharp compression obstacle, also known as “bucking.” In the case of front suspension, an improper amount of rebound damping can cause impact to the rider's hands as the front suspension kicks back directly toward the rider. Conversely, preventing the suspension from rebounding too slowly is also an important aspect of the quality of vehicle suspension setup. An improper amount of rebound damping, where the amount of damping is too high, can result in the suspension not returning quickly enough to respond to the next bump in a series of bumps, ultimately causing the suspension to “ratchet” down into a compressed state. Such a “ratcheting” sequence is commonly referred to as suspension packing. Packing can result in the suspension being overly stiff due to retained compression through the middle to the end of a series of bumps, causing the back of the vehicle to kick off the ground and pitch the rider forward (in the case of the rear suspension) and causing the suspension to get overly stiff and steering geometry to get steep and unstable (in the case of the front suspension). Compression damping settings are similarly important.
As the foregoing illustrates, what is needed in the art are improved techniques for assisting the operator of a vehicle to prepare and adjust one or more operating parameters of the vehicle for an optimum riding experience.